Pine tree roots house foundation

Tree Root Systems: Learn About Problem Tree Roots

Invasive tree roots are a common problem for homeowners and in commercial settings. They interfere with streets and sidewalks, sneak into septic lines and cause trip hazards. Tree root problems are not always solved by the removal of the tree, as the stump or remaining roots may continue to grow. It is best to look at the type of tree and the suckering ability of its roots beforehand and then deal with the issue on a case-by-case basis.

Understanding Tree Root Systems

Trees use their roots to provide stability and gather water and nutrients. The types of tree root systems vary from shallow to deep, wide to narrow. Some have massive taproots and little peripheral root growth.

Others, such as many conifers, have extensive root masses that spread far out from the base of the tree in search of resources. These types of trees have deeper spreading roots and surface feeder roots.

Feeder roots branch and send out smaller growths to capture every bit of water and food for the plant. Surface roots that grow large can break the surface of the soil

and cause tree root problems.

Tree Root Problems

Tree maintenance difficulties and safety are two primary root issues. Large root structures prevent mowing and other activities, and may pose a walking hazard.

Roots crack and crumble cement and concrete and may even damage building foundations if the plant is too close to a structure.

One of the most common tree root problems is introduction into plumbing or sewer systems. Invasive tree roots are seeking nutrients and water and such pipes draw them in for the growth. Once inside the pipes, they cause leaks and plug up the line. This poses an expensive and extensive repair that most homeowners would like to avoid.

Problem Tree Roots and Planting

Of course, hindsight is 20-20 and it is best to choose plants that have well controlled root systems in your garden. However, sometimes you purchase a home with existing trees or you might be uninformed when you install a problem plant.

Knowledge about problem tree roots and planting only those with non-invasive root systems is the ideal situation. Some tree root systems such as Japanese fir, Acacia and Vine maples are considered minimally invasive. CalPoly’s Urban Forests Ecosystems Institute has a list of other plants with low root damage potential and other attributes to help you avoid tree root problems.

How to Control Invasive Roots

The repair costs from invasive tree roots can add up. The wise homeowner should learn how to control invasive roots to avoid and minimize these problems.

Tree removal is often the only answer and the stump should be ground to prevent the continued growth of roots. Freshly cut stumps treated right away with glyphosate will usually kill the roots. If you cannot afford stump grinding, drill holes in the stump and cover it with soil or fill them with a stump decay accelerator.

Install a root barrier around young trees at a depth of 18 to 24 inches in a trench around the root zone.

Again, the best method to prevent tree root problems is prevention and proper tree selection and location.

RENEGADE GARDENER™

With some frequency I encounter homeowners concerned because a mature tree on their property was planted quite close to the house (usually by a previous owner). They are worried that the tree’s roots are going to grow into the foundation and cause it to buckle or crack, then possibly be further damaged by roots growing into these cracks.

Tree roots can cause damage to house foundations, but not in the manner above.

First, let’s address the concerns of homeowners in possession of homes with basements—Midwesterners, in other words. (Being from Minnesota, I believe I was in my mid-40s before I discovered that not every home in America has a basement.) It’s not the strength of the tree root, or its ability to penetrate a poured concrete or concrete block foundation that potentially can cause a problem, because the force of a tree root in and of itself is not capable of performing such a feat.

Foundation problems can and do result, however, from what tree roots are doing in the first place—sucking up water. Unless the soil around the house foundation is very dense and was properly compacted after the foundation was installed, tree roots can cause slumping and shifting of the soil as they draw out water. Tree roots grow larger each year underground, to the point where a mature tree will grow roots so large they may also loosen and heave soil due to their changing girth. It is the combined effect of these two root characteristics that can cause enough of an imbalance of pressure in the soil surrounding a house foundation that it may strain outward and crack.

Root growth will not enlarge these cracks. Tie a hemp rope tight around the trunk of a tree, and in three years you’ll see that the tree is girdling, unable to snap the rope. A tree root finagling its way into a crack in a vertical concrete basement foundation will not be strong enough to jackhammer concrete, or overcome the thousands of pounds of pressure resting on that portion of foundation.

Poured concrete foundations—slabs, I believe they are called—are a different matter. An oak or other large variety of tree planted near a concrete slab foundation (or concrete patio or sidewalk) that grows UNDER the concrete is in the soil unimpeded, and as it gains girth each year it certainly may cause the horizontal pad to be lifted and crack. What happens more often, however, is the root draws water, the soil slumps, and the pad cracks due to not enough pressure from underneath.

I would say ninety-nine times out of hundred, trees in our yards live their whole lifespan without damaging a house foundation. Remember, the length of a tree’s root system can easily be twice the height of a tree, meaning if roots always caused damage, we’d never be able to plant an oak or maple or linden within a hundred feet of a house.

The Renegade Gardener’s spawn flourishing in the Renegade Gardener’s basement.

You can ensure against the potential for root damage by not planting trees that get large closer than twenty feet from a house, but you need to go that far away, and farther, so the tree’s crown doesn’t hit the roof. I often plant small trees—magnolias, slim ornamentals—six to ten feet from a house foundation, and will plant dwarf evergreens as close as three. These plants do not develop massive, deep root systems, and are not going to draw so much moisture from the soil around the foundation that it will cause problems.

For mature trees near homes—I have a 150 year-old oak about ten feet from mine—best advice is keep them watered in summer, and keep the shrubs and perennials in your foundation plantings watered. This will keep your soil suitably compacted around the foundation.

A final question to readers in Florida and Oklahoma and California who don’t have basements: Where do you store all your junk? Where do you start your seeds under lights? Where do you put the ping-pong table and the drum kit?

Don Engebretson
The Renegade Gardener

Tree root problems

TREE ROOT PROBLEMS

Root systems are vital to the health and longevity of trees. All plants need water, oxygen, and nutrients. These are most readily available near the soil surface where precipitation infiltrates the soil and oxygen from the atmosphere diffuses into the porous soil. Most roots, therefore, especially the important, tiny, absorbing roots, proliferate near the soil surface. The majority of a large tree’s roots are in the upper 18″-24″ of soil. When space is available, roots can spread two to three times further than the branches. Tree roots are often associated with situations that cause damage to structures, pavements, and utilities. In almost every case, roots are not the cause of the problem.

ROOTS AND UNDERGROUND PIPES

Instances of pipes being broken by the growth of roots are rare, but blockage of damaged pipes is not uncommon. As roots enlarge, they may occasionally break the pipes and enter the cracks. More commonly, the pipes fail (especially at the joints) due to age or slight movement of the soil, allowing roots to invade. Moisture and nutrients released from ruptures can stimulate root growth toward the break in the pipe. Once a root enters a sewer pipe, the conditions of aeration, moisture, and nutrients are quite favorable for rapid growth. Species that are naturally found in wet areas such as poplars, willows, and silver maples, are commonly associated with clogged pipes. Blocked sewers usually must be cleared mechanically. Mechanical routing may be needed on an annual basis. Registered chemical treatments are available. The main advantage of these products is that they can be placed into the sewer as a foam for more effective contact with roots; however, it is essential to follow label directions. The only permanent solution to the problem, however, is to replace ruptured pipes. Modern materials and joints should prevent most problems in the future.

ROOTS AND PAVEMENT

If trees are too close to pavement, or if compacted soil forces large roots to grow very near the soil surface, roots can eventually lift pavement. When roots encounter a paved area, the only entry is often a gap between the soil and pavement. Future problems can be prevented at the time of planting by using smaller plants, providing a minimum distance of 4 feet between the tree and the pavement, or using mechanical barriers to prevent roots from growing under the pavement. Remedies for lifted pavements around mature trees often involve either moving the pavement away from the tree or pruning off the problem roots. Barriers are often installed after the roots are cut to prevent re-growth of the roots and recurrence of the pavement lifting. Cutting off the problem roots often causes stress and instability. Trees without sufficient root support can be blown over more easily in a storm.

ROOTS AND FOUNDATIONS

Roots are often blamed for damage to foundations. In reality, roots are rarely the cause of the problem. Though small roots may penetrate existing cracks in foundations, they are incapable of causing mechanical damage through their growth. Soil subsidence can result in damage to structures. Under very special circumstances roots can contribute to this problem. When soils are prone to shrinking substantially during periods of drought, and if foundations are shallow, roots can contribute to depletion of soil moisture under the foundation, causing it to subside.

SURFACE ROOTS

Major tree roots often grow within a few inches of the soil surface. Some species, such as maples, grow roots particularly close to the surface. Alternate freezing and thawing causes frost-heaving, which can expose roots that would otherwise remain below the soil surface. On slopes, soil erosion may also expose roots. These surface roots could become a foot hazard or cause difficulty in mowing, and are easily injured. Removing these roots may disrupt the moisture supply to the tree, causing serious stress. Covering them with soil could cut off the oxygen supply to the fine roots in the soil below. Both situations could lead to decline. The best solution is usually to mulch the area under the tree with compost and/or wood chips. These materials are porous enough to allow sufficient oxygen supply to the soil and may actually encourage fine root growth. Acting as an insulator, the mulch will minimize further frost-heaving and erosion. Another benefit is the replacement of highly competitive turf grass with mulch, which supplies nutrients as it decomposes. Grass removal is not necessary before the mulch is applied. If mulch is not an option, raise the soil surface by adding no more than two inches of halfcompost/ half-topsoil mix. An additional 2 inches can be added each year as necessary to raise the soil level sufficiently to cover the roots. The lawn can then be replanted, but the tree roots may reappear on the surface within a few years.

GIRDLING ROOTS

Tree roots that wrap around the base of the trunk can restrict the flow of water and nutrients up and down the trunk, leading to decline and dieback of the crown. Norway maples are most susceptible to damage from girdling roots, but they can occur in most trees. When roots circling inside of a pot in the nursery cause the problem, the tree seldom survives more than a decade in the landscape. On “balled & burlapped” plants, girdling roots develop for different reasons and the decline may take 20 to 30 years to develop. To prevent girdling roots in nursery stock, make sure that all circling roots on the outside of the root ball are eliminated at time of planting. Research shows that moderate disruption of the container root system does not increase stress. For large girdling roots on established trees, correcting the problem can be difficult. Removal of the girdling roots may cause enough damage to the root system to hasten the decline. Several roots may be intertwined, making it even more difficult. It is difficult to predict if removing the roots will be more damaging than leaving them alone.

GRADE CHANGES

Roots grow much closer to the soil surface than is often believed. Since roots are near the surface and depend on oxygen, raising the soil level around an established tree can have serious impact. This new soil will drastically reduce the oxygen supply to roots. On the other hand, removing just a few inches of topsoil can also remove much of the tree’s root system, severely stressing the plant. When grade changes are necessary, avoid changing the grade within the dripline of the tree. The fewer roots that are impacted, the better the chances that the tree will survive. Another alternative would be to construct a retaining wall outside the dripline to accomplish the grade change. If the grade change is necessary to improve site drainage, be sure to divert the excess water away from the tree.

SEVERING ROOTS

Balance between the tree’s crown (top) and root system is important for maintaining healthy trees. When roots are lost for any reason, the imbalance creates stress. A tree usually has 4 to 7 major roots. Cutting just one of them within a few feet of the trunk can remove up to 25 percent of the root system. In such situations, giving the tree extra water during summer dry periods and thinning the crown may help to minimize decline. During temporary excavation, such as for utility installation or repair, significant root loss may result, but if the soil is replaced soon afterward, roots can regenerate into the replaced soil and recovery is more likely. Extra care (primarily watering) will be required for many years during the restoration of the lost roots. When underground utilities must be installed close to a tree, tunneling or augering under the root system avoids damage altogether.

If you have trees on your property, you have most likely been reaping the variety of benefits that they provide. They enhance the beauty of your home, keep the air clean and help keep you cool when it gets hot. They are, however, capable of doing a lot of damage to your home and the surrounding areas as well if you aren’t careful. For instance, old branches can fall and do harm to your property. If you have your trees professionally trimmed periodically however, you can deal with this recurring issue.

There are other potential ways your property can be damaged however, and the scary part is, it can go completely unseen. We’re talking about the tree’s roots, which can grow out of control if not properly managed.

Often it’s poor planning on the part of the homeowner, who is responsible for the damage caused by tree roots. If you are careful when choosing and planting your trees, many problems can be avoided. The aim of this article is to advise you on both the proper planning and proper management of aggressive root systems.

How Tree Roots Work

First it’s a good idea to have a proper understanding of how tree root systems work. It is the roots that anchor the tree in the soil as it grows. Their job is to keep the tree stable while collecting water and nutrients to nourish it. Roots can actually sense the presence of water and nutrients in the soil and will move towards any sources of nourishment they can find. The plants have a vascular structure that can then draw the water and nutrients upwards and into the rest of the plant.

Roots are incredibly strong. They are able to grow up to three times the diameter of the branches, spreading throughout the ground as they grow. This is a slow process, taking years, and it means that for every tree you see, there is a very large part of it growing underneath the ground.

As tree roots grow larger, they displace more and more of the soil that they are growing within. This is often what causes the damage; the displaced soil can place a lot of pressure upon sidewalks, pipes, and other structures that are built under or on top of the soil. The roots are also capable of damaging landscapes as they push through the surface and become visible, ruining the aesthetic appearance of the area they’re growing in.

As tree roots grow underground, they seek water. This makes them a particular threat to pipes as they will grow towards any water sources that are nearby. In their endless search for water, they can force their way inside of pipes, breaking them apart and clogging them as they do so. They can also damage pipes by displacing soil; as the soil shifts, even a small amount, they can do serious damage to pipes, especially if they are older.

Older sidewalks are also susceptible to soil displacement. As the roots grow underneath the sidewalks, they can push them upwards, causing them to crack and buckle which creates the need for costly repairs.

There are several steps you can take to manage these problems however. As we mentioned it all starts with planning.

Planning Around Tree Roots

Before placing any trees in an area, make sure you know the location of any underground pipes so that you can avoid them as necessary. Simply having underground pipes doesn’t mean you can’t plant any trees; you simply have to take care with which species you choose. Maple trees are an example of a species which grows quickly but rarely causes damage with its roots. Buckeyes, pagodas, horse chestnuts, magnolia, and dogwood are other examples of non-invasive trees.

The least invasive trees available to you will vary depending upon your location. Check with your local Parks and Recreation department for a list of the best species to use.

Managing Tree Roots

In many cases, you can’t control where the trees are since the trees were either already planted when you acquired the property, or perhaps you are dealing with trees the city has installed around your property. Whatever the reason, there are still options open to you to manage the growth of aggressive roots.

Tree root barriers are often an effective method of controlling root growth. They are, simply put, walls that prevent roots from passing through. They are generally made of corrosion resistant materials such as plastic or fiberglass. Install them carefully, since an improperly placed tree root barrier can do more harm than good. They can damage trees themselves or even prevent water from draining properly so take care to follow instructions when placing them. They should reach a depth of at least two feet underground to redirect root growth properly.

Tree growth retardants are a popular fix for many people, however we do not endorse them since they tend to prevent the visible parts of the tree from growing without actually doing anything to control the growth of roots. If you are not able to find any of the aforementioned methods effective, you may have to remove the tree. In this situation, you should always hire a tree service professional because if the tree stump isn’t properly removed the roots may continue to grow.

For any and all assistance managing your trees, contact Mr. Tree today!

Tagged as: Aggressive Tree Roots, Root Damage, Tree Care, Tree Roots

What Can I Do About Problem Tree Roots?

Tree roots can cause big problems. Invasive roots can damage pathways, driveways and retaining walls, block drains and pipes, cause trip hazards, kill other plants in your garden and damage pools.

Whilst it may seem like a quick and easy solution to just remove the offending root, it’s generally not the best idea in the long run. The root systems of a tree are critical to its health and longevity as they carry nutrients, oxygen and water back to the tree.

If you’ve got a tree root problem, it’s important not to try and just cut the root out without very careful consideration, as you may end up destabilising the tree, making it a safety hazard, and potentially killing the tree.

What should I do for tree root problems?

Always seek the advice of a professional Arborist who can advise you on what action needs to be taken for your particular type of tree and the issues you have, to prevent further damage.

If the roots are relatively small and above ground, sometimes the roots can be pruned back without affecting the tree. This will depend on the type of tree, its size, the location of the tree root and the severity of the problem.

Having a tree root barrier installed can be a great solution to problem tree roots. Root barriers are a preventative measure that can basically train the tree’s roots to grow in a certain direction and away from footpaths, driveways and buildings. A root barrier will essentially hold roots at bay and reduce further damage.

The tree roots are exposed, and a trench is then dug around them. Roots are pruned, and a fungicide solution is applied to the ends of the cut roots. The root barrier is then positioned in the trench, and a layer of bentonite clay is poured into the trench, followed by layers of soil and further clay.

Installing a root barrier can eliminate the need to have a tree removed and allow the tree to live a long life. Installation should always be supervised by a qualified Arborist experienced in tree growth patterns, who will be able to advise on the best position to insert the barrier and ensure roots are protected to keep the tree healthy.

Depending on the extent of the damage and your particular tree’s root system, tree removal is sometimes necessary as a last resort. This should always be done by a qualified Arborist to minimize the risk of damage to your home and property.

The tree stump should be completely ground out to remove a potential food source for termites.

Which trees have the most invasive root systems in Brisbane?

As they say, prevention is better than cure, so if you have the opportunity to do so, always consider what type of trees and plants you put in your garden as well as where you’re going to put them, to prevent possible root damage down the track.

There are a large number of tree species that have aggressive root systems. Some of the most common include:

  • Figs (Ficus carica)
  • Umbrella trees (Schefflera actinophylla)
  • Eucalyptus trees (Eucalyptus globulus)
  • Jacaranda trees (Jacaranda mimosifolia)
  • Bottlebrushes (Callistemon sp.)
  • Paperbarks (Melaleuca quinquenervia)
  • Camphor Laurel (Cinnamomum camphora)
  • Weeping Willow (Salix babylonica)
  • Liquid Amber (Liquidambar styraciflua)

If in doubt, get some advice on what’s best for your home and garden, so you don’t have potentially costly headaches down the track.

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